A gas turbine engine may be used to power various types of vehicles and systems. A particular type of gas turbine engine that may be used to power aircraft is a turbofan gas turbine engine. A turbofan gas turbine engine conventionally includes, for example, five major sections: a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. The fan section is typically positioned at the inlet section of the engine and includes a fan that induces air from the surrounding environment into the engine and accelerates a portion of this air toward the compressor section. The remaining portion of air induced into the fan section is accelerated into and through a bypass plenum and out the exhaust section.
The compressor section raises the pressure of the air received from the fan section. The compressed air from the compressor section is then directed to the combustion section. In the combustion section, the compressed air enters the combustor, where a ring of fuel nozzles injects a steady stream of fuel. The fuel and air mixture is ignited in the combustor to form combustion gases from which energy is extracted in the turbine section.
To improve engine efficiencies, gas turbine engine designers and manufacturers continue to increase the operational temperatures within engines. At these ever-increasing temperatures, it becomes increasingly difficult to effectively cool the combustors and still maintain sufficient residual airflow for emissions and exit temperature (e.g., dilution) control. To address this difficulty, a dual-wall cooling approach (e.g., impingement and effusion) has been developed to reduce the combustor wall temperatures.
The dual-wall cooling approach uses conventional sheet metal construction with sliding joints and inserts to provide adequate jet velocity for major/quench holes. This approach has demonstrated promising reduction in wall temperatures, but also exhibits certain drawbacks. For example, it is susceptible to manufacturing tolerances, causing variation in cooling or pressure drop.
Hence, there is a need to provide a cooling approach for combustors and other dual-wall hot section structures that provides at least equivalent temperature reduction benefits as known dual-wall cooling approaches, while simultaneously reducing the susceptibility to manufacturing tolerances. The present invention addresses at least this need.